FIG. 10 shows a fuel cell of related art. This fuel cell 100 is made by disposing a negative electrode 102 and a positive electrode 103 respectively on the upper face side and the lower face side of an electrolyte membrane 101, placing a separator 105 on the upper side of the negative electrode 102 and sandwiching the peripheral vicinity of the electrolyte membrane 101 and the peripheral vicinity of the upper side separator 105 with an upper side gasket 106, and placing a separator 105 on the lower side of the positive electrode 103 and sandwiching the peripheral vicinity of the electrolyte membrane 101 and the peripheral vicinity of the lower side separator 105 with a lower side gasket 106.
With this fuel cell 100, hydrogen gas is supplied through multiple hydrogen gas passages 107 as shown by the arrow a. The hydrogen gas in the hydrogen gas passages 107 is guided toward a central part 105a of the upper side separator 105 as shown with an arrow. Oxygen gas is supplied through multiple oxygen gas passages 108 as shown by the arrow b. The oxygen gas in the oxygen gas passages 108 is guided toward the central part 105a of the lower side separator 105 as shown with an arrow.
As a result of hydrogen gas being introduced into the upper side central part 105a, hydrogen molecules (H2) come into contact with a catalyst included in the negative electrode 102, and as a result of oxygen gas being introduced into the lower side central part 105a, oxygen molecules (O2) come into contact with a catalyst included in the positive electrode 103, and electrons e− flow as shown with an arrow and a current is produced.
At this time, product water (H2O) is produced from the hydrogen molecules (H2) and the oxygen molecules (O2), and this product water flows through multiple product water passages 109 as shown by the arrow c.
In this fuel cell 100, to maintain resistance to corrosion of the gas passages 107, 108 and the product water passages 109, it is necessary for the gas passages 107, 108 and the product water passages 109 to be sealed. To achieve this, in the manufacture of the fuel cell 100, the upper side gasket 106 is sandwiched in the gap between the peripheral vicinity of the electrolyte membrane 101 and the peripheral vicinity of the upper side separator 105, and the lower side gasket 106 is sandwiched in the gap between the peripheral vicinity of the electrolyte membrane 101 and the peripheral vicinity of the lower side separator 105.
Here, it is desirable for the fuel cell 100 to be compact, and it is necessary for the upper and lower gaskets 106 to be made thin. Consequently, handling of the upper and lower gaskets 106 has been difficult, it has taken time for the upper and lower gaskets 106 to be disposed in the proper positions, and this has constituted a hindrance to raising fuel cell productivity.
As a method of resolving this problem, for example the ‘Manufacturing Method of a Silicone Resin—Metal Composite Body’ of JP-A-11-309746 has been proposed. According to this method, gaskets can be eliminated by forming a silicone resin (hereinafter, ‘seal’) around the peripheral part of the separator. An injection-molding mold for manufacturing a fuel cell separator of related art is shown in FIG. 11, and a separator manufacturing method of related art will now be described.
Referring to FIG. 11, by an injection-molding mold 110 being closed, a separator 113 is inserted in a gap between a fixed die 111 and a moving die 112 and a cavity 114 is formed by the fixed die 111 and the moving die 112, and by the cavity 114 being filled with molten resin as shown with an arrow, a seal 115 is formed on a peripheral part 113a of the separator 113.
By the seal 115 being formed around the peripheral part 113a of the separator 113 like this, the upper and lower gaskets 106 shown in FIG. 10 can be made unnecessary. Therefore, in the manufacture of the fuel cell, it is possible to dispense with a step of incorporating the upper and lower gaskets 106.
To prevent the gas passages and product water passages of the separator 113 from being corroded by the gases and product water, it is necessary for the entire surfaces of the gas passages and the product water passages to be covered. Because of this, it is necessary not only for the upper face and the lower face of the peripheral part 113a of the separator 113 to be covered by the seal 115, but also for the wall faces of the gas passages and product water passages in the peripheral part 113a to be covered by the seal 115.
To cover the entire surfaces of the gas passages and product water passages of the peripheral part 113a with the seal 115 to raise their resistance to corrosion like this, it is necessary to raise the precision of equipment such as the injection-molding mold 110, equipment costs consequently rise, and this constitutes a hindrance to keeping costs down.
And even if the precision of the equipment is raised, it is difficult to cover the entire surfaces of the gas passages and product water passages of the peripheral part 113a with the seal 115, and yield in the manufacture of the separators is likely to fall, and this has constituted a hindrance to raising fuel cell productivity. Thus, a fuel cell separator has been awaited with which it is possible to secure corrosion resistance of the separator and also raise productivity as well as keeping costs down.